I bought this thinking that it was Trek/Bontrager's solution for attaching a light to the back of a helmet. Yes, I thought the helmet strap was only for the top of the helmet. It attaches my flare 3 nicely to the back of my circuit helmet and allows me to be more visible and safer when I ride on NYC's streets.
I'm only rating it 4 stars because when you use for a helmet in this manner, you have to have a set of plier to attach it to your helmet. But it works!